Blade cleaning is a widely practiced technique in electrostatographic printers and copiers for removal of toner particles from surfaces (K. Seino, S. Yuge, M. Uemura; Journal of Imaging Science and Technology, 2003, Volume 47, 424). The part of the blade that contacts the surface to be cleaned is commonly a polyurethane. Urethanes are tough materials with a high degree of resilience that are well suited for making contact with a smooth surface.
The application of cleaning blades to web cleaning is reported in U.S. Pat. No. 6,453,134, the disclosure of which is incorporated by reference herein in its entirety. The web can be used as a transport element to carry a receiver through an electrophotographic printer and at the same time be used as a print substrate for process control. Toner patches are removed from the transport element after image density is measured with some type of radiation such as light emitting diodes (LEDs). The substrate to be cleaned is often a clear, insulating plastic such as poly(ethylene terephthalate) (PET). The cleaning blade typically includes a rigid stiffening plate supporting a flexible urethane rubber blade member. Preferred specifications for the urethane to obtain effective cleaning include a hardness of between 60 to 85 Shore A, an initial modulus between 500 and 1500 psi, a Bayshore resiliency above 30%, and a compression set lower than 25%.
The properties of urethane blades can be improved by surface coating over the urethane. U.S. Pat. No. 5,363,182, e.g., describes a blade body of urethane rubber and a surface coating of graphite particles in a nylon resin. A primer layer is used to enhance the adhesion of the filled nylon layer to the urethane blade. The coating serves to protect the urethane from degradation due to hydrolysis. The hydrolysis rate is often enhanced by the corona products produced by the chargers in the electrophotographic printer. The coating also has a low coefficient of friction and does not change the elasticity of the blade.
Urethane overcoats that are designed to be hard like a ceramic yet flexible like a polymer are part of a group of materials known as ceramers. As discussed in U.S. Pat. No. 5,968,656, ceramer overcoats are coated as layers of approximately 5 microns on relatively thick, resilient urethane base cushion “blanket” cylinders to provide transfer of toner from a photoreceptor to a receiver in electrophotographic printers. A preferred composition for the ceramers is of a urethane backbone made from isophoronone diisocyanate and a polyether diol. The backbone is branched by the addition of trimethylolpropane and 1,4-butane diol serves as a chain extender. The branched urethane is endcapped with 3-isocyanatopropyltriethoxysilane to provide alkoxysilane groups that can react with alkoxysilanes in a sol-gel reaction to form a polyurethane silicate hybrid organic-inorganic composite network (OIC) ceramer.
Urethane polymers containing fluorinated substituents are well known. One mode of introduction of the fluorinated component is from a fluoroether, either as an endcapper or from the diol into the polyurethane backbone. These materials are useful in a number of commercial applications.
US 2007/0244289 describes a method of making urethane based fluorinated monomers which can be used to prepare radiation curable coating compositions, and discloses that such monomers can be used to formulate a ceramer composition such as disclosed in U.S. Pat. No. 6,238,798. U.S. Pat. No. 6,238,798 describes ceramer coating compositions comprising colloidal inorganic oxide particles and a free-radically curable binder precursor which comprises a fluorochemical component that further comprises at least two free-radically curable moieties and at least one fluorinated moiety. In such compositions, the colloidal inorganic oxide particles can be surface treated with a fluoro/silane component which comprises at least one hydrolysable silane moiety and at least one fluorinated moiety. As discussed therein, aggregation of the inorganic oxide particles in such compositions can result in precipitation of such particles or gellation of the ceramer composition, which, in turn, results in a dramatic, undesirable increase in viscosity.
U.S. Pat. No. 7,120,380 describes pseudo-boehmite as an oil absorbing layer that employs fluorinated surfactants as cleaning aids for an endless receiver transport belt coating in an electrophotographic printer. Pseudo-boehmite is disclosed as in a transport member for an electrophotographic apparatus that displays high friction in US 2006/0165974. Pseudo-boehmite is disclosed as an oil absorbing layer that employs wax overcoats as cleaning aids in US 2007/0196151. Gamma-alumina is disclosed as an oil absorbing layer that employs siloxane surfactants as cleaning aids in US 2008/0107463. Gamma-alumina is disclosed as an oil absorbing layer that employs fluoro surfactants as cleaning aids in US 2009/0052964. The disclosures of all five of these patents and published applications are hereby incorporated by reference in their entireties.